Year	Number of
1990	212.81
1991	217.13
1992	220.11
1993	222.18
1994	225.22
1995	230.6
1996	240.05
1997	252.32
1998	267.37
1999	284.51
2000	303.59
2001	321.13
2002	339.9
2003	360.56
2004	381.49
2005	403.12
2006	420.54
2007	437.54
2008	458.91
2009	481.39
2010	505.4
2011	520.27
2012	536.69
2013	554.2
2014	573.39
2015	594.4
2016	614.33